1. Field of the Invention
The present invention relates to a dicing die-bonding film that is used in dicing of a workpiece under a condition where an adhesive for fixing a chip-shaped workpiece such as a semiconductor chip and an electrode member is pasted onto a workpiece such as a semiconductor wafer before dicing, a manufacturing method thereof, and a method of manufacturing a semiconductor device using it.
2. Description of the Related Art
A semiconductor wafer (workpiece) on which a circuit pattern is formed is diced into semiconductor chips (chip-shaped workpieces) (a dicing step) after the thickness thereof is adjusted by backside polishing as necessary. In the dicing step, it is common to wash the semiconductor wafer at an appropriate liquid pressure (normally, about 2 kg/cm2) to remove a cut layer. Next, the semiconductor chips are fixed onto an adherend such as a lead frame with an adhesive (amounting step), and then they are transferred to a bonding step. In the mounting step, the adhesive is applied onto the lead frame or the semiconductor chip. However, this method can hardly make an adhesive layer uniform, and a special apparatus and a long time are necessary for the application of the adhesive. Accordingly, a dicing die-bonding film is proposed that provides an adhesive layer for fixing chips that is necessary in the mounting step while adhering and holding a semiconductor wafer in the dicing step (for example, refer to Japanese Patent Application Laid-Open No. 60-57642).
The dicing die-bonding film described in Japanese Patent Application Laid-Open No. 60-57642 provides a peelable adhesive layer onto a support base. That is, the semiconductor wafer is diced while being held by the adhesive layer, the semiconductor chips are peeled off together with the adhesive layer by stretching the support base, and the individual semiconductor chips are collected and fixed onto an adherend such as a lead frame with the adhesive layer in between.
A good holding strength toward the semiconductor wafer and a good peeling property such that the semiconductor chips after dicing and the adhesive layer can be peeled off a support base integrally are desired for an adhesive layer of a dicing die-bonding film of this type so that a dicing impossibility, a dimensional error, or the like does not occur. However, it has never been easy to balance both characteristics. Especially when a large holding strength is required in the adhesive layer such as in a method of dicing a semiconductor wafer with a rotary circular blade, or the like, it is difficult to obtain a dicing die-bonding film that satisfies the above-described characteristics.
Then, in order to overcome such problems, various improved methods have been proposed (for example, refer to Japanese Patent Application Laid-Open No. 2-248064). In this document, a method is proposed that makes picking up of a semiconductor chip easy by providing an ultraviolet-ray curable pressure-sensitive adhesive layer between the support base and the adhesive layer, decreasing the adhering strength between the pressure-sensitive adhesive layer and the adhesive layer by curing the product with an ultraviolet ray after dicing, and peeling the two layers from each other.
However, even with this improved method, there is a case that it is difficult to have a dicing die-bonding film in which the holding strength during dicing and the peeling property after dicing is balanced well. For example, in the case of a large semiconductor chip that is 10 mm×10 mm or more or a very thin semiconductor chip 25 to 50 μm in thickness, the semiconductor chip cannot be picked up easily with a general die bonder because of the large area.
For such problems, Japanese Patent Application Laid-Open No. 2005-5355 discloses that the pickup property is improved by irradiating a portion corresponding to a pasting portion of a semiconductor wafer in a pressure-sensitive adhesive layer and curing the corresponding portion. However, when the dicing die-bonding film described in this document is used, there is a case that the adhesive constituting the die-bonding film overflows onto the cut face after dicing and with this the cut faces reattach to each other (blocking). As a result, there occurs a problem that pickup of a semiconductor chip becomes difficult.